1. Field of the Invention
This invention relates to the field of sports playing fields and more particularly to artificial playing fields.
2. Discussion of the Background
Modern playing fields for football, baseball, soccer, and other sports are typically multi-layered composites of natural and/or artificial materials. In designing such composites, two primary but often competing concerns are the athlete's safety and the hardness of the field. In most sports, a relatively hard field is desired for speed. However, a relatively soft field is equally desirable to protect the athletes from injuries due to contact with the field itself from tackling, jumping, falls, and the like.
Hard, fast fields commonly may have a relatively high and potentially harmful impact rating that can lead to injuries. Impact rating systems for fields vary widely and are determined in any number of different ways (e.g., dropping a weight on a portion of the field). Nevertheless, in each case, the rating is intended to relate to measuring the equivalent of, for example, a football player landing on his helmet during a game or being violently thrown to the field. A hard, fast field may well have an impact rating of 140-150 times gravity (140-150 g's). Softer fields may have a safer rating more on the order of 60-80 g's but such fields typically play too slow for many athletes, particularly higher level and professional ones.
In addition to the concerns of safety and hardness, other factors are involved in designing a field. In nearly all current sports fields, water drainage is very important as the field must be able to quickly and efficiently drain away water. However, combining the design issues of safety and hardness with water management often leads to conflicting results. As for example, a new field that begins as a relatively soft one may have sublayers of pea gravel or sand for drainage. The sublayers then tend to compact over time and can change the initially soft field into a harder one. Although an excellent drainage material, gravel and sands thus have their drawbacks.
Sports fields further need to present as uniform a playing surface as possible over the entire field. As indicated above, fields with sublayers of pea gravel can harden over time and change the field characteristics. Equally of concern is that they tend to do so in specific areas of the field (e.g., down the middle) destroying the uniformity of the overall playing surface. Attempts at replacing gravel sublayers for drainage have been tried but for the most part simply present their own new sets of problems.
Modular systems of artificial materials in particular have presented problems of irregularities between the pieces at the seams. Nevertheless, such modular systems of artificial materials have commercial appeal as they are much easier and faster to install than gravel and sand systems and are normally not as deep (e.g., one to three inches versus six to ten inches or more for fields with multiple layers of pea gravel). With football and soccer fields which are on the order of 80,000 square feet, gravel and sand systems can present significant consistency, time, and cost problems. Such problems can include sourcing a consistent quality of the materials in different parts of the country as well as simply hauling and handling the materials and uniformly spreading and compacting them in place.
In this light, the present invention was developed. With it, a multi-layered playing field composite is provided that is lightweight and modular. Additionally, the resulting field plays like a hard, fast one yet with the impact ratings of a relatively soft field. Further, the resulting field has excellent water drainage management and can be installed relatively quickly and easily.